Microscale control over collagen gradient on poly(l-lactide) membrane surface for manipulating chondrocyte distribution

A collagen gradient was constructed to interrogate cell adhesion on a poly(l-lactide) (PLLA) membrane surface. Utilizing a microinfusion pump, gradients of amino groups were generated on the PLLA surface by an aminolysis method. Immobilization of collagen onto the gradient surfaces was performed by glutaraldehyde (GA) coupling to form the collagen gradients. The –NH2 and immobilized collagen density profiles on the PLLA membranes were quantitatively determined by ninhydrin and hydroproline (Hyp) analysis, respectively. By using fluorescein isothiocyanate (FITC) labeled collagen (FITC-Col), the profile of the as-prepared collagen gradient was directly monitored by a fluorescence microscope. The scanning force microscopy and water contact angle studies revealed that the morphology and wettability of the modified membranes changed progressively as a function of position along the gradient surface. Rabbit auricular chondrocytes were cultured on the collagen gradient membranes to test their cellular response. The attachment and spreading behaviors of the chondrocytes were dependent on the surface collagen density. These results indicate a surface on which the variation of collagen gradient strongly modifies the biological response of chondrocytes.